In conventional multiple-input and multiple-output (MU-MIMO) pairing scheduling technology (i.e., first conventional technology), which relies on only downlink channel information between base station and user equipments (UEs), the base station performs, based on the channel information, greedy scheduling and pairing on the UEs in connected state to achieve the best pairing effect (i.e., obtaining the best channel capacity).
In the first conventional technology, the base station needs to obtain the downlink channel information of each of the UEs in the connected state by: using the UE feedback in frequency division duplexing (FDD)/time division duplexing (TDD) system (regular feedback or irregular feedback, where a typical channel feedback content includes: channel quality indicator (CQI) for downlink precoding, precoding matrix indicator (PMI), and rank indicator (RI)); or performing partial uplink channel measurement by using the channel reciprocity in the TDD system (typically, the uplink channel is measured by using the reciprocity between the uplink and the downlink channels and the obtained information of the downlink channel includes the MIMO channel matrix). In the latter way, the base station may perform the downlink channel precoding without the PMI/RI feedback.
The first conventional technology is applicable to the case of less users in the connected state and less users participating in the MU-MIMO (such as the long term evolution (LTE) system/LTE-advanced system), in which the complexity of the pairing scheduling is controllable and has little influence on the scheduling delay. However, if the first conventional technology is applied to the scene in which the number of the users in the connected state is more and the number of the users participating in the MU-MIMO is more (for example, if the conventional first conventional technology is applied to a large-scale antenna array system), the number of the users in the connected state and the number of the users participating in the MU-MIMO increase tremendously as compared with the LTE/LTE-A system, and the complexity of the pairing scheduling is increased significantly; accordingly, the scheduling delay becomes too long, the influence on the validity of the channel information is significant, and the actual throughput is affected.
The PF scheduling technology (i.e., second conventional technology) is a layer scheduling method widely used in cellular communication system, which takes both the UE channel quality and the historical throughput into account, and ensures the scheduling equity among the UEs while ensuring the system throughput. The PF scheduling method includes steps as follows.
The PF scheduling starts in the current transmission time interval (TTI); each UE in the connected state feeds back the CQI in a manner (such as periodic feedback or non-periodic feedback) agreed in advance between the UE and the base station; the base station calculates the possible maximum rate of each UE in the connected state in this scheduling based on the received CQI fed back by the UE in the connected state most recently; the actual average of the rates in the historical TTIs is filtered in a certain time window to obtain the filtered average rate; based on the ratio of the possible maximum rate in the current TTI to the filtered average rate, the scheduling priorities of all the UEs to be scheduled are calculated; and the PF scheduling in the current TTI is finished.
The second conventional technology may be considered as a branch for the UE scheduling scheme in the first conventional technology, and is applicable to a common UE schedule method. However, when too much UEs are scheduled using the second conventional technology, the channel information of all the UEs need to be obtained; and when the second conventional technology is applied to the large-scale antenna array system, the number of the users in the connected state and the number of the users participating in the MU-MIMO increase tremendously as compared with the LTE/LTE-A system, the complexity of the pairing scheduling is increased significantly; accordingly, the scheduling delay becomes too long, the influence on the validity of the channel information is significant, and the actual throughput is affected.